Terahertz (THz) radiation consists of electro-magnetic waves with frequencies of approximately 1011-1013 Hertz. This part of the electromagnetic (EM) spectrum is currently a rich research topic due to inherent advantages in the fields of communications, imaging, and spectroscopy. However, there are no well-established highly-efficient materials or techniques for the generation, detection, amplification and phase-sensitive processing of THz waves.
Conventional techniques for the manipulation of radio-frequency (RF) signals (i.e. <˜100 GHz) in the optical domain cannot be used for THz signals. RF photonics typically uses conventional electro-optic (EO) modulators to upconvert the RF signals onto optical carriers, though these modulators have decreasing performance beyond 40 GHz. Furthermore, there is no clear roadmap for using EO modulators in the high-frequency THz region.
Another challenge when utilizing THz radiation is detection. Although techniques exist for THz detection, they are generally considered to be relatively poor.